Effects of adsorbed polyaniline on redox processes on As2O3 surfaces

Polyaniline deposited on As2O3 surface resulted in a new material, which was characterized by infrared spectoscopy, thermogravimetry, differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and cyclic voltammetry, The mass percentage of polymer deposited on oxide surface is approximately 13%, The scanning electron microscopy images as well as the X-ray diffraction patterns provided conclusive evidence that the oxide surface is coated by the polymer. The cyclic voltammograms of the polyaniline adsorbed on As2O3 surface showed that the adsorbate exerts remarkable effects on redox processes on this oxide. The pure oxide exhibited two oxidation/rcduction peaks at 0.25/-0.06 and 0.47/-0.25 V attributed tentatively to the processes As2O3(s) + 6H(+) + 6e(-) = 2As(s) + 3H(2)O and As(s) + 3H(+) + 3e(-) = AsH3(g), respectively. The polyaniline-coated sample exhibited a better-defined voltammogram in which the first oxidation peak of the oxide had its intensity increased about four times. (C) 2000 Academic Press.